1. Technical Field
This invention relates to safety latches, and more specifically to biased safety latches that secure a door without positive user engagement.
2. Background Art
A door is generally an opening in a wall (or other partition), often equipped with a hinge and which can be moved to leave the opening accessible, or to close it more or less securely. Hinged doors have typically been the predominant type of door used within homes, businesses, or other structures for egress/regress between various rooms or even the outside of a structure. Doors are used in structures of all kinds, allowing passage between inside and outside, or among internal rooms. The purpose of a door opening is to allow people, animals, and objects to pass, as well as for ventilation. The purpose of door closure is to prevent passage of air, reduce air drafts, create an enclosed space that can be heated or cooled more effectively, privacy and noise reduction, and to help prevent the spread of fire.
Limiting passage between areas partitioned by doors has historically been controlled by latches or locks. When a partitioned area contains a hazard, danger, or vulnerability, a latch or lock may secure the door against passage by an unauthorized person or animal. For example, a latch may be used to prevent a child's access to a home office or prevent a pet from entering an off-limits area. Similarly, when a person desires privacy within a specific unit of a structure, a latch or lock may be engaged to prevent passage of other people occupying the same structure. Latches and locks have been traditionally located midway between the top and bottom of a standard door allowing individual users of varying heights access to the device and effectively access to the room. Such placement of latches enables children to also disengage the latch and pass through a door. Furthermore, some doors are not necessarily latched when in closed but unlocked positions and may be opened merely by applying pressure to any surface of the door and pushing. Thus, their effectiveness in preventing children and pets from passing through the door may be limited. Because of dangers lying beyond a door, or because of desires to limit the access of children and pets to certain units, access limiting devices have been developed and are known in the art. Commonly known devices used on swinging doors include free-spinning door knob covers and security chains mounted out of reach of children.
Regrettably, many access limiting devices become a hassle for adults to operate because of the additional access limitations they create for adult users. When such devices become obstructive to adults, such devices are frequently disengaged or bypassed, thus eliminating their beneficial use. An example of such an obstruction is an engaged security chain mounted on the interior of a door that may effectively limit the travel of the door when a child attempts to open it. However, the engaged safety chain on the interior of the door prohibits an adult user of the door from entering from the exterior side. Many other access limiting devices are only overrideable from one side of the door and equally become a nuisance to an adult user.
Another nuisance for adults, which exists in many safety latch devices, is required positive user interaction to engage the latching mechanism. This positive interaction requirement may limit protection compared to systems that lock automatically when the door closes. For example, a child, the infirmed or pet may be put in danger when a parent or guardian simply forgets to latch a door to a foreseeably dangerous area.
The prior art contemplates numerous safety latches. The prior art, however, suffers from flaws not present in the current invention. Several latches exist, such as chain latches and the like, that require user assistance to engage the latch. Most latches, however, mount to the molding surrounding a door and therefore any force applied to the latch pulls on the nails mounting the molding. This significantly weakens the strength of the latches. Many latches, also, simply are not overrideable from both sides of a door, and require time and effort to effectively put them to use. Similarly, most safety latches do not comprise a biased locking feature that enables automatic locking without user input, while those that do comprise a bias feature suffer from inconsistency in latch engagement. Almost all latches on the market today lack the ability to mount to doors with various shapes of molding surrounding them. Lastly, the prior art safety latches lack the ability to grant to a user the power to adjust the latch to allow a door to open only to a desired displacement. It is desirable therefore, to have a safety latch device that comprises the following features: a latch that is predisposed to a latchable position and automatically engages when a user attempts to open a door, a latch that is overrideable from either side of a door, a latch that is biased to automatically return to a latchable position after overridden, a latch that will mount to a door regardless of the shape of the molding surrounding the door, a latch that is easy to install and use, a device that is adjustable to allow a door to open to various pre-determined angular displacements, a latch that is disengageable thus allowing a door to open and close freely, a latch that mounts to the door frame rather than the molding surrounding a door, a latch with a finger protector to keep fingers from being smashed in the door, and a latch that is installable on either side of a door and at a variety of vertical positions on a door and doorframe. Prior inventions contemplate devices with some of these features, but none disclose a device capable of all of the listed features. Accordingly, what is needed is a door safety latch capable of all of these features.